A&P CH.17-1 BLOOD COMP & ERYTHROCYTES

What are the functions of blood?

Transport, regulation, and protection.

What is the composition of whole blood?

Matrix is nonliving fluid called plasma. Cells are living blood cells called formed elements
▪ Formed elements
– Erythrocytes (red blood cells, or RBCs)
– Leukocytes (white blood cells, or WBCs)
– Platelets

What is hematocrit?

Percentage of blood volume made up by erythrocytes, about 45%

What is the buffy coat

Layer between plasma and erythrocytes in centrifuged blood; contains leukocytes and platelets; less than 1%

What is plasma composed of?

About 90% water, plus nutrients, gases, hormones, wastes, proteins, ions. Main protein is albumin

What are the functions of plasma?

Transport substances, and maintain osmotic pressure

What is the function of erythrocytes?

Dedicated to respiratory gas transport

Name key structural features of erythrocytes aiding gas transport.

Biconcave shape, no mitochondria, filled with hemoglobin, flexible

Describe hemoglobin structure

4 polypeptide chains (2 alpha, 2 beta), each with an iron-containing heme group.

How many oxygen molecules can one hemoglobin carry?

Four.

Which part of hemoglobin binds oxygen?

The iron atom in each heme group.

What other gas can hemoglobin bind?

Carbon dioxide

Define hematopoiesis. Where does it occur?

Formation of all blood cells in red bone marrow

Formed elements arise from which cell?

Hematopoietic stem cell (hemocytoblast)

Define erythropoiesis

Formation of red blood cells

Summarize erythrocyte production.

1.Stem cell → 2.myeloid cell → 3.proerythroblast → 4.erythroblasts → 5.reticulocyte → 6.erythrocyte

Where is erythropoietin produced? Its function?

Kidneys (and some liver); stimulates RBC production.

What are reticulocytes?

Immature RBCs with some ribosomes; reticulocyte count shows RBC formation rate

Name dietary requirements for erythropoiesis.

Amino acids, lipids, carbohydrates, iron, vitamin B12, and folic acid

What is anemia?

Low oxygen-carrying capacity of blood.

List types of anemia and causes

Blood loss, not enough RBCs produced (iron-deficiency, pernicious, renal, aplastic anemia), too many RBCs destroyed (sickle cell)

What is pernicious anemia?

Lack of intrinsic factor prevents B12 absorption, decreasing RBCs.

What is sickle-cell anemia?

Mutation in hemoglobin causes crescent-shaped RBCs that break easily and block vessels.

Define polycythemia

Excess RBCs; can be induced by blood doping (adding stored RBCs to increase oxygen capacity).